Mr. Griffith on Shotgun Patterns,
1897 https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA234 p. 243 Turnover case longer than the chamber
No. 9 2 1/2 case with 1/8 turnover
No. 10 3/8 turnover
No. 11 & No. 12 with 2 3/4 and 3 cases in 2 1/2 chambers = patchy patterns, clustering, and frequent balling Pattern examples on p.244
p. 245 balling or clustering
p. 247 Summary of patterns,
Field, March 5, 1898
No. 9 - 1/8 turnover better pattern % than 10, 11 & 12
Pressures with 3 Dr. Schultze with 1 1/8 oz.
(pressures converted from long tons/sq. inch to psi by Burrards formula)
2 1/2 case with 1/8 turnover 2.13 tons = 6,040 psi
2 1/2 case with 3/8 turnover 3.03 = 9,060 psi
2 3/4 case in 2 1/2 chamber 3.22 = 9,700 psi
3 case in 2 1/2 chamber 3.71 = 11,345 psi
When long cases are used in short chambers, the paper overlaps the cone and causes greater resistance to passage of the shot and wads. The pressure then goes up considerably, while muzzle velocity and recoil are both increased.
